ACSM Exercise Specialist Workshop

1
ACSM Exercise Specialist Workshop

• Metabolic Calculations
• Tutorial

2
Purpose of Metabolic Calculations

• Under steady-state conditions, VO2 provides a
  measure of the energy cost of exercise
• The rate of O2 uptake at maximal exercise
  indicates the capacity for O2 transport and
  utilization
• Peak VO2 serves as the gold standard criterion
  measure of cardiorespiratory fitness
• At steady state, and in combination with CO2
  output, VO2 can provide information about type of
  fuel use during exercise
• Determine work rates to be used in the
  development of exercise prescription

3
Expression of VO2

• Absolute- Liters per minute (L?min-1)
• Used to convert consumption to a rate of energy
  expenditure
• Relative- mL per kg body weight per min
  (mL?kg-1?min-1)
• Used to compare VO2 among varying body sizes
• Gross oxygen consumption- Total consumption rate
  under any circumstances, either in absolute or
  relative describes rest plus exercise
• Net oxygen consumption- Consumption rate above
  resting oxygen uptake (approx. 3.5
  mL?kg-1?min-1) describes exercise

4
RER and RQ

• RER-Respiratory Exchange Ratio
• Ventilatory measurement
• Reflects gas exchange between lungs and pulmonary
  blood
• Exceeds 1.0 during heavy exercise due to
  buffering of lactic acid which produces CO2

• RQ-Respiratory Quotient
• Cellular Respiration and substrate utilization
• 0.7 Fat
• 1.0 Carbohydrate
• 0.8 Protein
• Equivalent to RER only under resting or
  steady-state conditions
• Can never exceed 1.0
• RQ is used to estimate energy expenditure,
  however, when RQ is not available, assume
• 5 kcal ?L-1

5
Estimation of Energy Expenditure

• When VO2 cannot be measured directly, estimations
  can be made during steady-state exercise (will
  overestimate VO2 if not at steady-state)
• Equations are based on relating mechanical work
  rate to metabolic equivalents
• Equations are appropriate for general clinical
  and lab use

6
Estimation of Energy Expenditure

• Equations can be used for
• Estimating or predicting energy expenditure
• Designing an exercise prescription to determine
  the exercise intensity associated with a desired
  level of energy expenditure

7
Cautionary Notes

• The inter-subject variability for VO2 may be as
  high as 7
• Appropriate for steady-state submaximal aerobic
  exercise
• Any variable that changes the metabolic
  efficiency results in loss of accuracy (e.g.,
  orthopedic limitations, holding handrail on
  treadmill, etc.)
• Assumes that a metabolic cart or gas analyzers
  and flow indicators are calibrated and used
  properly
• Despite these caveats, metabolic equations
  provide a valuable tool for exercise
  professionals

8
Conversion Factors

• 1L 1000 mL
• 1kg 2.2 lbs
• 1mph 26.8 m?min-1
• 1lb of fat 3500kcal
• 1 MET3.5 mL?kg-1?min-1
• 1 W 6 kgm?min-1
• 1L O2?min-1 5 kcal?min-1
• 1 in 0.0254m2.54 cm

MEMORIZE
MEMORIZE
MEMORIZE
9
Located in Appendix D of GETP6
10
Conversion Flowchart
METS
lb fat loss/gain
X 3.5
? 3.5
?3500
X 3500
mL?kg-1?min-1
Total kcal
X Tot min
? Tot min
X BW
? BW
X 1000
X 5
mL?min-1
L ?min-1
Kcal?min-1
? 1000
? 5
11
Walking (1.9?3.75 mph)

• VO2 (0.1?S) (1.8 ?S ?G) 3.5
• Horizontal Vertical Rest
• S speed in m?min-1 (convert if needed)
• G grade in decimal form (i.e., 5 is 0.05) if
  0 grade, then vertical0
• R resting component
• NOTE VO2 is reported as mL?kg-1?min-1

12
(No Transcript)
13
Running (gt5.0mph)

• VO2 (0.2 ?S) (0.9 ?S ?G) 3.5
• Horizontal Vertical Rest
• All variables are the same as for walking
• NOTE VO2 is reported as mL?kg-1?min-1

14
(No Transcript)
15
Leg Ergometry

• VO2 (10.8 W/M) 7
• M mass (weight) of subject in kg
• W Work rate in watts,
• convert when necessary
• 1 W 6 kgm?min-1
• kgm?min-1R ?D ?f
• R resistance in kg
• D distance of the fly wheel
• 6m for Monark
• 3m for Tunturi
• f frequency in rpm
• NOTE VO2 is reported as mL?kg-1?min-1

16
(No Transcript)
17
Arm Ergometry

• VO2 18(W/M) 3.5
• Find work rate the same as leg ergometry
• Major difference
• D2.4 for Monark
• NOTE VO2 is reported as mL?kg-1?min-1

18
(No Transcript)
19
Stepping Ergometry

• VO2 (0.2 ?f) (1.33 ?1.8 ?f ?h) 3.5
• fstepping rate
• hheight of step in m
• NOTE VO2 is reported as mL?kg-1?min-1

20
Question 1

• VO2 (0.1x85.76)(1.8x85.76x.06)3.5
• VO2 8.576 9.26 3.5
• VO2 21.34 mL?kg-1?min-1
• 21.34/3.5 6.1 METs

21
Question 2

• VO2 (0.2x241.2)(0.9x241.2x.01)3.5
• VO2 48.24 2.17 3.5
• VO2 53.9 mL?kg-1?min-1
• VO2 53.9 mL?kg-1?min-1 x 68.0 kg3665.2
  mL?min-1
• VO2(L?min-1) 3665.2 mL?min-1/1000 mL?L-1 3.67
  L?min-1
• Kcals?min-1 3.67 L?min-1x5 kcals ?L-1 18.4
  Kcals?min-1
• Kcals in 40 minutes 18.4 Kcals?min-1 x 40min.
  736 kcals expended in 40 minutes

22
Question 3

• 50 kg man walking at 75 VO2 reserve. Max VO2
  2.4 L?min-1. What speed at a grade of 12.
• 2.4 L?min-1 2400 mL?min-1
• 2400 mL?min-1 50 kg 48 mL?kg-1?min-1
• 48 mL?kg-1?min-1 x 0.75 36 mL?kg-1?min-1
• 36 (0.1)(x) (1.8)(x)(0.12) 3.5
• 36 0.1x 0.21x 3.5
• 32.5 0.31x
• x 104.8 m?min-1/26.8 m?min-1 3.9 mph

23
Question 4

• VO2 (0.2xS)(0.9xSxG)3.5
• 45.0 mL?kg-1?min-1 0.2x87.6)(0.9x187.6xG)3.5
• 45.0 mL?kg-1?min-1 37.52 168.8(G) 3.5
• 3.98 168.8 (G)
• 0.024 G or 2.4

24
Question 5

• VO2 (18 x W/M) 3.5
• where W 0.5kg x 2.4m x 50rpm
• w60 kg?m?min-1 or 10 watts
• VO2 mL?kg-1?min-1 (18 x 10)/50 3.5
• VO2 180/50 3.5
• VO2 3.6 3.5
• VO2 7.1 mL?kg-1?min-1

25
Question 6

• 176 lbs/2.2 80 kg
• Warm Up
• 2.5 x 3.5 8.75 mL?kg-1?min-1
• 8.75 mL?kg-1?min-1x80 kg700 mL?min-1
• 700 mL?min-1 /1000 mL?L-1 0.7 L?min-1
• 0.7 L?min-1 x 5 kcals?L-1 3.5 kcals?min-1 x 5
  min. 17.5 kcals in 5 min.

26
Question 6... continued

• Exercise
• 4.5 METs 15.75 mL?kg-1?min-1
• 15.75mL?kg-1?min-1
• x 80kg 1260 mL?min-1 1.26 L?min-1
• 1.26 L?min-1 x 20 min 25.2 L x 5 kcal ?L-1 126
  kcals in 20 min.
• 4 METs 14 mL?kg-1?min-1
• 14 mL?kg-1?min-1 x 80 kg 1120 mL?min-1 1.12
  L?min-1
• 1.12 L?min-1 x 15 min 16.8 L x 5 kcal ?L-1 84
  kcals

27
Question 6continued

• Cool Down
• 2 METs 7 mL?kg-1?min-1/80kg 560 mL?min-1
• 560 mL?min-1/1000 mL?L-1 0.56 L?min-1
• 0.56 L?min-1 x 5 min 2.8 L
• 2.8 L x 5 14 kcals
• 17.5 126 84 14 241.5 Kcals

28
Question 7

• 140 lbs 63.6 kg
• TM _at_ 3.2/0
• VO2 8.5763.512.08 mL?kg-1?min-1
• 12.08 x 63.6 768.29 mL?min-1
• 768.29/1000 0.768 L?min-1
• 0.768 x 10 7.7 l 38.5 kcals
• TM _at_ 3.4/2 50.5 kcals
• TM _at_ 3.0/5 59.5 kcals
• Total Kcals 148.5
• 148.5 x 3 445.5/week
• 3500 x 15 52,500 kcals
• 52, 500 kcals/445.5 118 weeks _at_ 3 days/week

29
Question 8

• MET level of person with VO2 of 55 mL?kg-1?min-1?

55 mL?kg-1?min-1 3.5 mL?kg-1?min-1 per MET
15.7 METs
30
Question 9

• 60 kg women with a VO2 of 2400 mL?min-1. What is
  her MET level?
• 2400 mL?min-1 60kg 40 mL?kg-1?min-1
• 40 mL?kg-1?min-1 3.5 mL?kg-1?min-1 per MET
  11.4 METS

31
Question 10

• 70 kg person using Stepper _at_ 18 steps?min-1, 25
  cm step
• VO2 (0.2 x f)(1.33 x 1.8 x H x F) 3.5
• VO2 (0.2 x 18) (1.33x1.8x0.25x18)
• VO2 3.6 10.8
• VO2 14.4 mL?kg-1?min-1 or 4.1 METs

32
Question 10continued

• 70 kg person on Monark _at_ 750 kg?m?min-1
• 750 kg?m?min-1 / 6 kg?m?min-1 per watt 125
  watts
• VO2 (10.8x125)/70 7
• VO2 18.9 7 25.9 mL?kg-1?min-1 or 7.5 METs
• (NOTE may get 7.4 METS if use 6.12 kg?m?min-1 as
  1 watt)

33
Question 10continued

• 70 kg person on Monark arm ergometer _at_ 350
  kg?m?min-1.
• 350 kg?m?min-1 58.3 watts
• VO2 (18x58.3)/70 3.5
• VO2 14.99 3.5
• VO2 18.49 or 5.3 METs

34
Question 11

• Who is exercising harder, Fred or Pete?
• Fred(72 kg)
• VO2 (0.2x160.8) (0.9x160.8x0.1)3.5
• VO2 32.16 14.47 3.5
• VO2 50.13 mL?kg-1?min-1 or 14.3 METS

• Pete (55 kg)
• Power 2.5kg x 6m x 60rpm 900 kg?m?min-1 or 150
  watts
• VO2 (10.8 x 150)/55 7 36.45 mL?kg-1?min-1
  or 10.4 METS

• FRED is working harder

35
Question 12

• Desired exercise intensity 8 METs what is the
  grade at 3 mph
• 3 mph x 26.8 m?min-1 per MPH 80.4 m?min-1
• 28 mL?kg-1?min-1 (0.1x80.4) (1.8x80.4xG)
  3.5
• 28 8.04 144.7(G) 3.5
• 16.46 144.7 (G)
• G 11.4

36
Question 13

• Functional capacity of 70 kg male completing
  stage 5 (3mph/12) of Balke protocol.
• 3 mph 80.4 m?min-1
• VO2 (0.1x80.4) (1.8x80.4x0.12)3.5
• VO2 8.04 17.37 3.5
• Relative VO2 28.9 mL?kg-1?min-1 or 8.3 METs
• Absolute VO2 2023 mL?min-1 or 2.02 L?min-1

37
Question 14

• MET level of man running _at_ 7mph and 5 grade
• 7 mph 187.6 m?min-1
• VO2 (0.2x187.6)(0.9x187.6x0.05)3.5
• VO2 37.52 8.44 3.5
• VO2 49.46 mL?kg-1?min-1 or 14.1 METs

38
Question 15

• What is kcal utilization over 20 minutes on the
  cycle ergometer if VO2 1745 mL?min-1.
• 1745 mL?min-1 1.75 L?min-1
• 1.75 L?min-1 x 5 kcals?L-1 8.75 kcals?min-1
• 8.75 kcals?min-1 x 20 min 175 kcals expended
  over 20 minutes

39
Questions